Just wanted to share my experience with passthrough in SPMC 12.4.1.
Have recently moved my OUYA from the lounge to the playroom.
I used to use XBMC for OUYA with passtrhough in the lounge with my Onkyo amp, I could get AC3 & DTS working using the trick of switching off/on the amp.

In the playroom I just installed a Yamaha YAS-101 soundbar which only has optical & coax digital inputs.
I'm running an optical toslink from my Sony Bravia to the Yamaha. Passthrough of both Dolby Digital & DTS are working perfectly without having to switch the soundbar on & off. Both DD/DTS gave me static on the actual TV speakers, but setting the TV to external audio only and passing through to the soundbar via optical works great.
Seems I'm quite lucky with the Sony TV though, as many TV brands don't passthrough DD/DTS from a HDMI source (something to do with HDCP, which is ridiculous as that should only apply to HD audio, as in DTS Master Audio & Dolby TrueHD).